1. Field of the Invention
The present invention relates to dielectric electronic components, such as a dielectric filter or a dielectric duplexer, which are used in mobile communication devices such as cellular phones, and which include a plurality of resonators arranged in a row.
2. Description of Related Art
A dielectric duplexer, which is an example of a dielectric electronic component of the type referred to above, is typically configured in the following manner. A plurality of resonators are arranged in a row in a dielectric ceramic block. Each of the resonators is formed through coating, with an internal conductor, the inner wall surface of a through-hole formed in the dielectric ceramic block. A predetermined circumferential surface of the dielectric ceramic block is coated with an external conductor. The resonators are divided into two groups. One group serves as a transmission section which is coupled with an input terminal pad formed on the predetermined circumferential surface in spaced relation to the external conductor. The other group serves as a receiver or reception section which is coupled with an output terminal pad formed on the predetermined circumferential surface in spaced relation to the external conductor. An antenna terminal pad is formed on a mounting surface of the dielectric duplexer in spaced relation to the external conductor in such a manner as to be coupled with the innermost resonator of the transmission section and the innermost resonator of the reception section.
A dielectric filter is another example of a dielectric electronic component of the type of interest here.
Conventional dielectric electronic components having the above-described configuration suffer the disadvantage that the attenuation characteristics thereof vary substantially from component to component. This is due to various factors such as variations involved in molding of the associated dielectric ceramic blocks which preclude obtaining the desired attenuation characteristics. Further, with the advancement and diversification of mobile communication devices, an increased demand has arisen for dielectric electronic components, such as dielectric filters and dielectric duplexers, which have various different attenuation characteristics.